1. Field of the Invention
The present invention relates to a water-based ink for ink-jet recording, an water-based ink set for ink-jet recording, and a treatment agent.
2. Description of the Related Art
In order to improve the optical density (OD value) and the chromaticness, it has been suggested that a water-dispersible polymer is contained in a water-based pigment ink (for example, Japanese Patent Application Laid-open Nos. 2006-2141 corresponding to United States Patent Application Publication No. 2006/0058420 and Japanese Patent Application Laid-open No. 2012-87309 corresponding to United States Patent Application Publication No. 2006/0058420).
However, it is demanded for the water-based pigment ink to further improve the optical density (OD value) and the chromaticness.
On the other hand, a water-based ink set for ink-jet recording has been suggested, wherein a treatment agent, which unstabilizes a dissolved state or a dispersed state of a colorant (coloring agent) contained in a water-based ink for ink-jet recording, is combined with the water-based ink for ink-jet recording in order to improve the optical density (OD value) (for example, Japanese Patent Application Laid-open No. 2006-159422).
However, it is demanded for the water-based ink set to further improve the optical density (OD value). Furthermore, it is also demanded for the water-based ink set to improve the chromaticness in the color recording.